From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56447) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1azj4G-0003M9-C0 for qemu-devel@nongnu.org; Mon, 09 May 2016 07:09:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1azj4E-0001Rf-C6 for qemu-devel@nongnu.org; Mon, 09 May 2016 07:09:39 -0400 References: <20160427153345-mutt-send-email-mst@redhat.com> <20160427142331.GH17926@8bytes.org> <20160427172630-mutt-send-email-mst@redhat.com> <20160427145632.GI17926@8bytes.org> <20160427180007-mutt-send-email-mst@redhat.com> <1461770135.118304.152.camel@infradead.org> <20160427211635-mutt-send-email-mst@redhat.com> <1461784617.118304.181.camel@infradead.org> <20160428172039-mutt-send-email-mst@redhat.com> <1461856314.33870.98.camel@infradead.org> <20160428182341-mutt-send-email-mst@redhat.com> From: Paolo Bonzini Message-ID: <57306FE4.4050006@redhat.com> Date: Mon, 9 May 2016 13:09:24 +0200 MIME-Version: 1.0 In-Reply-To: <20160428182341-mutt-send-email-mst@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V2 RFC] fixup! virtio: convert to use DMA api List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" , David Woodhouse Cc: Joerg Roedel , Kevin Wolf , Wei Liu , Andy Lutomirski , qemu-block@nongnu.org, Christian Borntraeger , Jason Wang , Stefano Stabellini , qemu-devel@nongnu.org, peterx@redhat.com, linux-kernel@vger.kernel.org, Amit Shah , iommu@lists.linux-foundation.org, Stefan Hajnoczi , kvm@vger.kernel.org, cornelia.huck@de.ibm.com, virtualization@lists.linux-foundation.org, Anthony PERARD On 28/04/2016 17:37, Michael S. Tsirkin wrote: > > All the internally-emulated devices *can* be either translated or > > untranslated. That's just a matter of software. Surely, you currently > > *can't* have translated assigned devices (until someone implements the > > whole VT-d page table shadowing or whatever), so you'll be barred from > > assigning a device to a slot which *previously* had an untranslated > > device. But so what? Put it in a different slot instead. > > Unfortunately people got used to be able to put any device > in any slot, and built external tools around that ability. > It's rather painful to break this assumption. Once you move to PCIe, a lot of things become more complicated. This is just one of them; instead of needing half a dozen PCI bridges, you'll need half a dozen plus one. Paolo